1. Field of the Invention
This invention relates to methods and apparatus for cardiopulmonary resuscitation and is particularly directed to improved methods and apparatus for performing direct heart massage.
2. Prior Art
In order to resuscitate a patient victim of a cardiac arrest, it is necessary to provide an adequate artificial circulation of oxygenated blood to the vital organs by reestablishing the pumping function of the heart at values as close as possible to the physiological prearrest condition. Such a cardiac pumping function must be instituted at the earliest possible stage. It is documented that a cardiac arrest results in irreversible brain death if a sufficient blood flow is not reestablished within a critical period of time from the moment of the cardiac arrest. Such a period of time is measured ranging between four and six minutes.
In order to reestablish the pumping function of the heart, two methods of cardiopulmonary resuscitation have been used heretofore: external or closed cardiac massage, and internal or open cardiac massage. Closed cardiac massage consists of applying pressure on the anterior chest wall and alternately releasing such pressure. In the vast majority of cases, closed chest compressions produce a severe low flow state, Raymond E. Jackson: Basic Cardiopulmonary Resuscitation; Emergency Medicine, American College of Emergency Physicians. Open chest cardiopulmonary resuscitation improves hemodynamics, resuscitation and the chance of surviving cardiac arrest. Cerebral blood flow achieved with open chest techniques has been shown to be near normal physiological values. There are several case reports of patients who have been resuscitated with direct cardiac massage when attempts with closed chest cardiopulmonary resuscitation have been unsuccessful, Advanced Cardiac Life Support Textbook, American Heart Association, page 42. However, few physicians today are skilled in the technique of direct cardiac massage. Since most cardiac arrests occur outside of a hospital and since most patients cannot be brought to a facility where a thoracotomy and direct cardiac massage can be performed in less that 15 minutes of total arrest time, the applicability of direct cardiac massage has been limited ACLS textbook, page 42. In addition to that, this technique is often characterized by many physicians as a rather grossly traumatic procedure, often seen as a desperate terminal attempt to resuscitate an arrested heart.
The aforementioned drawbacks of the two prior art techniques of heart massage have been recognized by Prisk and Johnson, who proposed a new method and apparatus for which they obtained a patent, U.S. Pat. No. 3,496,932, issued Feb. 24, 1970. The method and apparatus described by Prisk and Johnson includes an inflatable bladder, insertable through the subxyphoideal region into a space between the sternum and the heart via a trocar-cannula assembly. In order to accommodate the inflatable bladder and its stem, the sharp three-sided tip of the trocar must have a comparably large diameter, as illustrated in FIG. 4 of the Prisk and Johnson patent. However, the larger the sharp three-sided trocar tip, the more likely are injuries to the heart, coronaries or surrounding organs. In addition to the risk inherent in the size of the sharp tip of the trocar, the blind advancement of a trocar with a sharp tip in the thoracic cavity has been proposed by Prisk and Johnson. Such blind advancement carries extremely high risk of puncturing and/or lacerating the heart, coronary vessels or the surrounding structures, with devastating consequences. Prisk and Johnson's proposed position of blindly inserting the trocar between the sternum and the pericardial sac is, indeed, an extremely risky procedure; this space being very narrow, while it is virtually impossible to insert the trocar into the other designated position, i.e. within the pericardial sac, this space being only virtual, since the visceral and parietal pericardium are in contact, separated only by a thin film of pericardial fluid. Furthermore, the device proposed by Prisk and Johnson lacks any mechanism for locating the position of the sharp tip of the trocar and lacks any safety mechanisms to prevent or avoid injuries, such as puncturing of the heart or coronary vessels. Moreover, an inflatable bladder with a laterally flexible stem, as proposed by Prisk and Johnson, lacks the required stability for maintaining its central position to effectively compress the heart. Also, the proposed inflatable-deflatable bladder has no guidance, thus lacking the ability to properly impress direction of the compressions toward the vertebral column, allowing the heart to be displaced during the phase of compression laterally to the column, and not maintaining the heart in position between the vertebral column and the sternum, as required for effective pumping and resulting in ineffective compression of the heart. Given the individual variability in the size and depth of the thoracic cage the device of Prisk and Johnson is inadequate in that it has no means to adapt to the various depths of the thoracic cavity and ignores the variability in the distance between the sternum and the vertebral column. Finally, the method of insertion of the Prisk and Johnson bladder is a multistep manual procedure, which is necessarily time-consuming and conflicts with the need for a rapid institution of cardiopulmonary resuscitation.
Buckman and Badellino in their PCT application No. PCT/US 93-06886 with international filing date Jul. 20, 1993, describe a plunger-like apparatus for intrathoracic direct substernal heart massage comprising a heart contacting member having a surface which is at least partially concave for contacting the heart and handle means attached to the heart for manually manipulating the apparatus.
With regard to the critical issue of entering the chest cavity to use their plunger-like device, in a way that prevents injuries to the intrathoracic organs, and is more practical than a traditional thoracotomy, Buckman and Badellino disclose a "small thoracotomy", which they describe as a full thickness incision by sharp dissection, from side to side of the chest wall, of a width ranging from about three and a half inch to about one inch.
Although a thoracotomy of such a reduced size is indeed an improvement over a traditional thoracotomy, because it is more expedite, still it is not the solution to the problem of entering the chest cavity safely to introduce means for heart compression on a patient with cardiac arrest. Buckman's reduced thoracotomy still cannot prevent the occurrence of pneumothorax, i.e. the collapsing of the lungs. As a matter of fact, with the incision size required by the sizes of the devices as described by Buckman and with the incision sizes actually disclosed by Buckman, pneumothorax is an unavoidable occurrence associated with Buckman's devices.
Pneumothorax is obviously a non-acceptable complication in a patient in cardiac arrest who has a critical need for oxygen. A pneumothorax requires the placement of a chest tube to re-expand the lungs, which is another invasive surgical procedure, and adds problems to problems and morbidity to morbidity, and which cannot be practically performed for instance on the field at the site of a cardiac arrest if the cardiac arrest, as most of them do, has occurred outside a hospital setting.
In reality, in prior art, such as in Prisk's invention, an incision of one inch or so is required, and possibly the introduction of the inflatable-deflatable balloon by Prisk may even require a smaller incision than the incisions disclosed by Buckman and Badellino. With that regard, the device proposed by Buckman and Badellino hardly seems to offer a real advantage or be an improvement over Prisk. Yet quite an emphasis is placed in the minimized dimension of the surgical incision required to pass Buckman's device into the chest cavity, to the extent that the procedure of chest massage is named by Buckman and Badellino as minimally invasive.
On the contrary, the drawbacks of even a small thoracotomy such as the one proposed by Buckman, which still causes pneumothorax, are completely overcome with this invention, which resolves the problem of introducing a heart massaging member into the chest cavity without causing pneumothorax. The width of passage through the chest wall needed to insert the heart massaging members disclosed in parent application Ser. No. 07/921,301 by Zadini et Al., in application Ser. No. 08/100,573 by Zadini et Al. and in this present Application can be much smaller than the sizes reported by Buckman and Badellino. Due to the very small width of the passage through the chest wall, the devices disclosed in parent application Ser. No. 07/921,301 by Zadini et Al., application Ser. No. 08/100,573 by Zadini et Al. and in this present Application can take advantage of a location for entry into the chest cavity in the left parasternal region in a skin area corresponding to the intrathoracic anatomical area designated "sine pleura". The choice of the area "sine pleura" prevents precisely the insurgence of pneumothorax, i.e. collapsing of the lung, which inevitably occurs every time the pleural cavity is inadvertedly entered. With regard to the occurrence of pneumothorax, due to the fact that the area "sine pleura" is a substantially restricted area, the choice of such area is only meaningful if the opening passage through the chest wall is significantly small, such as it can be achieved with all the embodiments described in parent application Ser. No. 07/921,301 by Zadini et Al., application Ser. No. 08/100,573 by Zadini et Al. and in this present Application. Being the width of the area "sine pleura" such a small area, only the Zadini's devices can enter the chest safely without causing collapsing of the lungs.
With regard to another critical issue, i.e.the problem of avoiding injuries to other intrathoracic organs besides the pleural cavity and the lungs, when entering the chest cavity, such as the heart, which is laying just beneath the anterior chest wall, Buckman's disclosed method of entry into the chest cavity is of an entry by sharp dissection with sharp surgical instruments. No different from Prisk's entry by sharp dissection with a trocar.
In particular, Prisk, page 2, lines 68-69, discloses "a trocar and cannula assembly" which "are used as tools to expedite the placement of the bladder within the chest". Prisk's bladder is equivalent to Buckman's plunger-like, heart massaging member. Such tools for the placement of the bladder within the chest are precisely the equivalent of the Buckman's "sharp surgical instrument" Buckman's device, no differently from and no better than Prisk's device, is inserted into the chest after a passage is opened through the chest wall and entry by sharp dissection into the chest cavity is carried out by the sharp tip or edge of a surgical instrument, such as a surgical blade, as clearly and unequivocally is repeatedly disclosed by Buckman in the specification and also in his claims. For instance, page 1, line 8 "a heart massager which is introduced through a relatively small surgical incision made in the chest wall"; page 8, lines 30, 31 and page 9 lines 1 and 2 "The instant invention is related to massagers and a particular method for their usage that allows each massager to be inserted through a small surgical opening made in the chest wall, so as to allow to directly contact the antero-lateral surface of the human heart"; page 9, lines 30, 31 and page 10 lines 1 through 4 "In its operation and in general manner, the massager is inserted into the left chest via small surgical incision. The massager has a heart contacting member that is subcutaneously inserted through the incision and into the interior of the chest so that the now substernal massager may be placed on the anterior and lateral surface of the ventricular chambers of the heart". Page 6, lines 19 through 20, "surgically separating the intercostal space inserting the heart massages through the intercostal space, etc. Page 27, lines "after a surgical incision is made a sharp surgical instrument is used to provide sharp dissection preferably in the fourth intercostal space, thereby allowing for the entrance of the finger of the operator which is used to locate, by finger palpation, the apex region of the heart.
Therefore the first entry into the chest cavity, in front of the underlying heart, is of a sharp tip or of a razor-like blade of a surgical knife, and is no different from the sharp, razor-like tip of the Prisk trocar. The chances of injuring the underlying heart, which is in contact with the anterior chest wall are still there either that the razor-like blade of a surgical knife is used or a sharply tipped trocar is used.
Notwithstanding the fact that Buckman's entry into the chest is by sharp dissection, no less and no better than Prisk's, Buckman and Badellino at page 3, lines 23-24 of their application seem to favorably compare their method of inserting the device into the chest cavity over Prisk's method by stating: "it is desired that the heart massager not only be devoid of a pointed tip, etc." There seems to be suggested that, unlikely Buckman's heart massaging member which is devoid of a pointed tip, Prisk's heart massaging member does have pointed tips, etc.
However, Prisk's heart massaging member, being an inflatable-deflatable bladder, has no pointed tips nor sharp edges at all.
In particular Prisk's balloon is "devoid of any sharp tip that may unnecessarily and inadvertedly damage body elements" no more and no less than Buckman's and Badellino's heart massaging member.
Buckman and Badellino do not disclose an entry by blunt dissection into the chest cavity but only of inserting a blunt heart massaging member, or more precisely, of inserting a heart contacting member devoid of pointed tips or sharp edges, through a passage already opened through the chest wall by sharp means.
However the absence of any pointed tips or sharp edges in heart massaging members is no novelty that Buckman and Badellino can claim.
In fact other heart contacting members for cardiac massage as well, such as all the well known Direct Mechanical Ventricular Assisting Devices described by Anstadt, and many others, are indeed devoid of any sharp tips or sharp edges and are inserted into the chest cavity devoid of any sharp tips and sharp edges after a thoracotomy, i.e. after a full thickness incision of the chest wall carried out by sharp instruments, which is precisely the method used also by Buckman and Badellino. G. L. Anstadt et. al., Trans. Amer. Soc. Art if. Int. Organs Vol. XII, 1966; Mark P. Anstadt et. al., Chest, 1991, Vol. 100, Mark W. Wolcott et. al., Surgery, 1960, Vol. 48, No. 5; Theodor Kolobow et. al., Trans. Amer. Soc. Artif. Int. Organs Vol. XI, 1965; W. Rassman et. al., Journal of Thoracic and Cardiovascular Surgery, 1968, Vol. 56, No. 6; David Goldfarb, Prog. Cardiovasc. Dis., 1969, Vol. 12, No. 3; W. J. Kolff, Progress in Cardiovascular Diseases, 1969, Vol. XII, No.3; Peter Schiff et. al., Trans. Amer. Soc. Artif. Int. Organs Vol. XV, 1969; W. Rassman et. al. and Peter Schiff et. al., R. Bartlett et al., Ann. Emerg. Med. 13, Part 2, 1984; M. Anstadt et al., Resuscitation 21, 1991; P. Safar et al., Am. J. Emerg. Med. 8, 1990.
As far as Prisk in concerned, Prisk teaches precisely to introduce into the chest cavity, through a passage already opened by sharp means, such as his trocar is, his heart massaging member which includes a flexible tube with a closed round distal end and a deflated bladder around the tube. Prisk therefore teaches to enter the chest cavity by the means of sharp dissection, then to introduce a heart massaging member which is devoid of any sharp tips or sharp edges. That is precisely the method disclosed by Buckman.
With regard to the further advancement of the heart contacting member within the chest cavity into the substernal region between sternum and heart, after entry into the chest cavity is accomplished with sharp means, it is quite obvious that no sharp means is needed after a passage has been opened through a wall delimiting the chest cavity. No sharp means is needed to advance further into the chest cavity, because the chest cavity where the heart massaging member has to be placed, i.e. the substernal space, is devoid of any structure that needs to be cut through. Therefore, not having to cut through anything, it is obvious that a heart massaging member be devoid of any pointed tips or sharp edges in its transit within the chest cavity.
Furthermore the heart massaging member does not have to travel within the chest cavity because the heart is just there, in contact with the internal surface of the thoracic cavity.
Therefore, besides the fact that inserting a heart contacting member being "devoid of sharp tip that may unnecessarily and inadvertedly damage body elements", as disclosed by Buckman, is not at all, as it will be shown, the problem that needs to be resolved, the introduction into the chest cavity of a "heart contacting member which is "devoid of sharp tip that may unnecessarily and inadvertedly damage body elements" is not novel over Prisk's invention itself and over others' prior art such as the Direct Mechanical Ventricular Actuation Devices of Anstadt and others.
No matter how blunt or how well devoid of sharp tips and edges is the heart massaging member inserted for the purpose of direct cardiac compression, it is precisely the problem of first entry, i.e. of opening the way to access the chest cavity by means of a safe method, which constitutes the main unresolved problem by the prior art, and which Buckman and Badellino fail to resolve. In Buckman and Badellino it is the cutting blade which cuts the deepest layer of the chest wall, that surfaces and makes first its access into the chest cavity. No matter how small can the penetration be into the chest cavity of such a sharp blade or tip, and how carefully can be carried out by the operator, still the entry into a chest cavity in Buckman and Badellino is not an entry by blunt dissection. Indeed the heart massager of Buckman and Badellino is and can only and solely be inserted after a full thickness incision is made through the chest wall including the last layer of tissue lining the chest cavity.
Buckman and Badellino do not disclose in their application any means for blunt dissection, nor entry by blunt dissection.
In fact they call for "sharp dissection" provided by a "sharp surgical instrument" after a first surgical incision of the skin is made. Nowhere in their specification is disclosed entry into the chest cavity either by a blunt instrument opening its way into the chest cavity or by a digital blunt dissection. Entrance of the finger of the operator is allowed only after a sharp dissection of the chest wall by a sharp surgical instrument is carried out, and is used for the purpose of locating the apex of the heart.
The main issue of a safe entry is not to make a skin incision to pass the superficial layer represented by the skin and or the subcutaneous tissue, but to avoid a sharp surgical dissection of the chest wall, because the sharp dissection of the chest wall may inadvertedly lead to cutting injuries of intrathoracic organs. Particularly, what has to be avoided is a sharp dissection which separates the deepest final layer of chest wall so as to avoid accessing the chest cavity and entering with a sharp surgical instrument into the chest cavity.
All the embodiments disclosed in Buckman and Badellino preclude the possibility that their devices are advanced and/or entered into the chest cavity by blunt dissection through the chest wall because they are too wide to allow blunt dissection. More specifically, such dimensions are just less than about three inches for the device of FIGS. 1 through 8, page 12 lines 25-26, and just less than about one inch for the device of FIGS. 9-11, page 12, line 30. In fact, at page 2,0 lines 10-11, it is acknowledged that this umbrella-like embodiment is inserted through the chest wall by a surgical incision of less than about one inch.
The key issue is not so much to insert into the chest cavity a heart massager devoid of any sharp tips, which is not novel over Prisk, but is to introduce a massager of said characteristics via a safely made entry into the chest cavity via blunt means, not by potentially highly risky means such as a pointed tip or a razor-like surgical blade. In view of the obviously critical status of a patient in a cardiac arrest and the need for performing urgently and safely, Buckman's device does not represent any advantage over Prisk's device. Buckman's device is only an alternative way of pumping the heart. The claimed advantage by Buckman of performing a minimally invasive by a small surgical incision is already present in Prisk and therefore not novel over Prisk.
If direct cardiac massage can be of any practical utility and be performed by paramedics in the field, at the site where cardiac arrests occur, the specific issue of entry into the chest cavity safely and expeditiously is the main issue to be resolved, and this problem is indeed resolved with this invention.
By disclosing means and methods of entering the chest cavity by blunt dissection, this invention resolves the key problem of implementing direct cardiac massage without causing pneumothorax, or other injuries to the intrathoracic organs including the heart.
Thus, none of the prior art methods and apparatus for cardiac pulmonary resuscitation have been entirely satisfactory.
A device having features for safe entry into the chest such as a blunt entry into the chest for the purpose of direct cardiac compression and a method of inserting a heart massager into the chest after a safe entry such as a blunt entry into the chest has never been described in any prior art and is subject matter of this invention.